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        "%matplotlib inline"
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        "\n# Label Propagation digits active learning\n\n\nDemonstrates an active learning technique to learn handwritten digits\nusing label propagation.\n\nWe start by training a label propagation model with only 10 labeled points,\nthen we select the top five most uncertain points to label. Next, we train\nwith 15 labeled points (original 10 + 5 new ones). We repeat this process\nfour times to have a model trained with 30 labeled examples. Note you can\nincrease this to label more than 30 by changing `max_iterations`. Labeling\nmore than 30 can be useful to get a sense for the speed of convergence of\nthis active learning technique.\n\nA plot will appear showing the top 5 most uncertain digits for each iteration\nof training. These may or may not contain mistakes, but we will train the next\nmodel with their true labels.\n\n"
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      "source": [
        "print(__doc__)\n\n# Authors: Clay Woolam <clay@woolam.org>\n# License: BSD\n\nimport numpy as np\nimport matplotlib.pyplot as plt\nfrom scipy import stats\n\nfrom sklearn import datasets\nfrom sklearn.semi_supervised import label_propagation\nfrom sklearn.metrics import classification_report, confusion_matrix\n\ndigits = datasets.load_digits()\nrng = np.random.RandomState(0)\nindices = np.arange(len(digits.data))\nrng.shuffle(indices)\n\nX = digits.data[indices[:330]]\ny = digits.target[indices[:330]]\nimages = digits.images[indices[:330]]\n\nn_total_samples = len(y)\nn_labeled_points = 10\nmax_iterations = 5\n\nunlabeled_indices = np.arange(n_total_samples)[n_labeled_points:]\nf = plt.figure()\n\nfor i in range(max_iterations):\n    if len(unlabeled_indices) == 0:\n        print(\"No unlabeled items left to label.\")\n        break\n    y_train = np.copy(y)\n    y_train[unlabeled_indices] = -1\n\n    lp_model = label_propagation.LabelSpreading(gamma=0.25, max_iter=5)\n    lp_model.fit(X, y_train)\n\n    predicted_labels = lp_model.transduction_[unlabeled_indices]\n    true_labels = y[unlabeled_indices]\n\n    cm = confusion_matrix(true_labels, predicted_labels,\n                          labels=lp_model.classes_)\n\n    print(\"Iteration %i %s\" % (i, 70 * \"_\"))\n    print(\"Label Spreading model: %d labeled & %d unlabeled (%d total)\"\n          % (n_labeled_points, n_total_samples - n_labeled_points,\n             n_total_samples))\n\n    print(classification_report(true_labels, predicted_labels))\n\n    print(\"Confusion matrix\")\n    print(cm)\n\n    # compute the entropies of transduced label distributions\n    pred_entropies = stats.distributions.entropy(\n        lp_model.label_distributions_.T)\n\n    # select up to 5 digit examples that the classifier is most uncertain about\n    uncertainty_index = np.argsort(pred_entropies)[::-1]\n    uncertainty_index = uncertainty_index[\n        np.in1d(uncertainty_index, unlabeled_indices)][:5]\n\n    # keep track of indices that we get labels for\n    delete_indices = np.array([])\n\n    # for more than 5 iterations, visualize the gain only on the first 5\n    if i < 5:\n        f.text(.05, (1 - (i + 1) * .183),\n               \"model %d\\n\\nfit with\\n%d labels\" %\n               ((i + 1), i * 5 + 10), size=10)\n    for index, image_index in enumerate(uncertainty_index):\n        image = images[image_index]\n\n        # for more than 5 iterations, visualize the gain only on the first 5\n        if i < 5:\n            sub = f.add_subplot(5, 5, index + 1 + (5 * i))\n            sub.imshow(image, cmap=plt.cm.gray_r, interpolation='none')\n            sub.set_title(\"predict: %i\\ntrue: %i\" % (\n                lp_model.transduction_[image_index], y[image_index]), size=10)\n            sub.axis('off')\n\n        # labeling 5 points, remote from labeled set\n        delete_index, = np.where(unlabeled_indices == image_index)\n        delete_indices = np.concatenate((delete_indices, delete_index))\n\n    unlabeled_indices = np.delete(unlabeled_indices, delete_indices)\n    n_labeled_points += len(uncertainty_index)\n\nf.suptitle(\"Active learning with Label Propagation.\\nRows show 5 most \"\n           \"uncertain labels to learn with the next model.\", y=1.15)\nplt.subplots_adjust(left=0.2, bottom=0.03, right=0.9, top=0.9, wspace=0.2,\n                    hspace=0.85)\nplt.show()"
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